Even with the recent development of blockbuster kinase inhibitor drugs like Gleevec, leukemias are still high on the list of deadly cancers. One reason for this is that patient response to inhibitor drugs is monitored by in- direct means (hematological remission, cytogenetic response, mRNA expression levels). We are combining two emerging methods: our peptide-based targeted intracellular kinase sensors and Multiple Reaction Monitoring (MRM) mass spectrometry to develop a kinase assay technology that will provide direct information about kinase inhibition from patient material. The strategy will also be compatible with simultaneous analysis of more than one kinase at a time, so the systems-level biology of phosphorylation signaling can be addressed. In this pilot study, we will examine various parameters to determine the optimal sensor concentration, cell number, analytical protocols and statistical analysis to obtain meaningful kinase activity data from patient material. We will also optimize the sample handling protocols for collecting, processing and storing the patient material prior to the kinase assay. Upon successful demonstration and optimization of this technique, we will be poised to expand this project through additional technological development using the R33 mechanism, and/or further study of signaling biology in leukemia through a hypothesis-driven mechanism. We anticipate that our technology will provide unprecedented levels of sensitivity and detail for examining kinase activity in primary patient cells, and may someday become a tool for monitoring inhibitor drug effects in relatively 'real-time,' giving physicians the opportunity to adjust dosage to maximize the positive outcomes of kinase inhibitor treatment for their patients.